A. Field of the Invention
The present invention relates to an organic ink composition for a glass substrates and a process for its application and, more specifically to an organic ink composition of the type which is curable by ultra-violet radiation, for printing labels, designs or any other decoration on glass bottles,
B. Description of the Related Art
There are some known inorganic and organic pigment compositions in the market, which provide an acceptable coloration mainly for the printing and decoration of plastic and paper articles. However, those pigment compositions have not been considered suitable for application on glass substrates mainly because of its weak resistance to water, solvents, abrasion, etc.
There is a number of well known radiation curable ink compositions for screen printing, including metallic pigments such as copper, silver, cadmium, chromium, manganese, etc. Examples of such ink compositions are disclosed in U.S. Pat. Nos. 3,957,694; 3,968,056 and 3,989,644 all of Bolon et al, mainly suitable for screen-printing on printed circuits.
It has been an increased interest of glassmakers, specifically of glass bottle makers, to use organic inks for labeling or decorating glass bottles, mainly for environmental preservation purposes and reduce the energy needs, as well as for complying with ambient regulations.
It is also known a number of organic compositions, pigmented or not, which are applied and cured by ultra-violet to infra-red radiation, for the most diverse purposes such as providing privacy, solar radiation control, abrasion strengthening, etc., examples of these organic compositions are disclosed in the U.S. Pat. Nos. 4,923,754 and 4,946,874 both of Lee et all; U.S. Pat. No. 5,514,521 of Kobayashi; U.S. Pat. No. 5,178,952 of Yamamoto et al; and U.S. Pat. No. 5,262,450 of Vera et al.
The application of these pigments or coatings is commonly limited to plastic and paper substrates, printed circuits, etc., but no information has been available to applicant regarding glass applications, mainly because of a poor adhesion or anchoring to the very smooth surface of the glass substrates, as well as because of their poor resistance to the water, solvents and abrasion for rough handling
U.S. Pat. No. 5,731,359 of Kamen et al, disclose a pigmented ink composition including a radiation curable component and a pyrrolopyrrol or isoindoline pigment, to provide a red or yellow color, which apparently can be applied by hot stamping from a foil or directly to a substrate and then cured by radiation.
Finally, U.S. Pat. No. 5,696,177 of Noguchi et al discloses a composition intended, among other, for glass surfaces comprising (i) a linear copolymer containing a first component of a monomer selected from alkyl methacrylate, acrylonittrile and styrene, and a second component of a hydrophilic monomer, and (ii) a resin obtained by esterifying a part of epoxy groups present in an epoxy resin which can be selected, among others, from epoxy-uretane resins. The linear polymer (i) is present in an amount of 20 to 80 parts by weight, and said resin (ii) is contained in an amount of 80 to 20 parts by weight. This composition may contain a silane adhesion promoter; a polyamide, and additives, without specifying the amounts thereof.
Those inks apparently have been suitable for application on disposable (no-returnable) glass bottles.
Therefore, some adhesion promoters, photo-initiator such as the Irgacure 184 from Ciba Geigy, strengthening agents, storage stabilizers, photosensitizes, crosslinking agents and so forth, have been introduced into the ink compositions and coatings in order to improve their resistance to the bottle filling process, the multiple alkaline washing process and rough handling, but sill they have not been considered suitable for imparting the desired properties for application to returnable glass bottles.
In accordance with the present invention, it is provided an ultraviolet radiation curable organic ink composition, comprising 80% to 95% by weight of an epoxy-polyurethane-based ink; 0.5% to 8% by weight of an additive including a mixture of polyethylenic waxes and polythetrafluorethylenic waxes; an adhesion promoter which can be added to the ink formula or independently applied as a primer on the glass substrate before the decoration process, and which includes a silane in a concentration of 0.15% to 3% by weight; and 1% to 8% by weight of a blocked aliphatic polyisocyanate catalyst that promotes a polymerization reaction and additionally a crosslinking reaction between the epoxy-polyurethane-based ink and the adhesion promoter, when heated to at about 160 to 200xc2x0 C., forming an interpenetration network (known as IPN) formed by the ink composition on the glass substrate, that
is specifically suitable for glass substrates;
has an increased adherence to a glass substrate because of a strong interpenetration network formed by the ink composition on the glass substrate, after heating the glass substrate to about 160 to 200xc2x0 C., caused by a crosslinking reaction between the epoxy-polyurethane-based ink and the primer, suitable promoted by a blocked aliphatic polyisocyanate catalyst;
surprisingly has a desired strengthening to the washing, before and after the filling process, as well as a suitable resistance to chemicals and resistance to the abrasion and heavy duty to which non-returnable glass bottles are subjected;
can be calcined at the furnace when it is recycled as cullet into a molten glass mass, without affecting the properties of the glass mass because it does not contain toxic metals such as lead, cadmium, hexavalent chromium, etc.;
is environmentally suitable because it does not generate noxious combustion gases nor hot-house gases;
reduces the ink consumption because it has a specific gravity which is about four times less heavier than the vitrifiable ceramic paints which have commonly been used for the decoration of glass bottles;
provides a greater yield per weight unit and saves energy and space because it does not need big furnaces for heating the paint;
provides more intense and bright colors and a more wide range of colors than the ceramic paints;
has a better adherence to the glass substrate because of the crosslinking reaction between the epoxy-polyurethane-based ink and the adhesion promoter, after it is heated, forming the interpenetration network on the surface of the glass bottles and because of the specific application method by which it is applicable.
Furthermore, in accordance with the present invention, it is provided a process for the preparation and application of the above disclosed ultraviolet radiation curable organic ink composition, comprising: a) preparing an ultra-violet radiation curable ink composition by mixing 80% to 95% by weight of an epoxy-polyurethane-base ink composition; and 0.5% to 8% by weight of an additive prepared from a mixture of polyethylenic waxes and polythetrafluorethylenic waxes, strongly stirring the mixture; b) adding an adhesion promoter primer composition comprising 0.15% to 3% by weight of a silane; c) adding from 1 to 8% by weight of a blocked aliphatic polyisocyanate catalyst; e) applying the prepared ink composition on the glass substrate, by serigraphy, tampography or the like and curing the ink composition by exposing the coated surface to an ultraviolet radiation; f) heating the substrate by passing it through a heating lehr to increase the temperature of the substrate between 160xc2x0 C. to 200xc2x0 C. to promote a crosslinking reaction between the epoxy-polyurethane-based ink and the adhesion promoter primer, forming an interpenetration network; and g) applying a lubricant agent including an oleic acid-based product as a gas or vapor, and/or spraying an aqueous emulsion of an ethoxylated polyethylen-derivative.
It has also been found that the adhesion promoter can be preliminary applied as a primer on the glass substrate before the decoration process, instead of combining it at the composition, although this adds an additional step to the application (decoration) process.
Furthermore, for the application of the primer to a glass surface, the primer may me conveniently hydrolyzed by the addition of water, and then preparing a solution with the hydrolyzed primer in a mixture of water and ethyl alcohol acidified with acetic acid or carbon dioxide, to be applied to the glass surface by spraying, or dipping or wiping the bottles in said solution, and then drying by heating at 100xc2x0 C. to 150xc2x0 C. for 5 to 25 minutes.
So that the above composition in combination with the disclosed process for its preparation and application, provides all the above-disclosed advantages over the known prior art.
It is therefore a main object of the present invention, to provide an ultraviolet radiation curable organic ink composition specially suitable for glass substrates and glass bottles, which has a desired strength to the washing with water and chemicals, before and after the bottle-filling process, as well as a suitable resistance to the severe abrasion and heavy duty to which non-returnable glass bottles are subjected;
It is also a main object of the present invention, to provide an ultraviolet radiation curable organic ink composition, of the above disclosed nature, which has an increased adherence to a glass substrate because of a strong interpenetration network formed by the ink composition on the glass substrate, after heating the glass substrate to about 160 to 200xc2x0 C., caused by a crosslinking reaction between the epoxy-polyurethane-based ink and the primer, promoted by a blocked aliphatic polyisocyanate catalyst;
It is also a main object of the present invention, to provide an ultraviolet radiation curable organic ink composition, of the above disclosed nature, which may be calcined at a furnace when it is recycled as cullet into a molten glass mass, without affecting the properties of the glass mass because it does not contain toxic metals such as lead, cadmium, hexavalent chromium, etc. and which makes it is environmentally suitable because it does not generate noxious combustion gases nor hot-house gases;
It is also a main object of the present invention, to provide an ultraviolet radiation curable organic ink composition, of the above disclosed nature, which reduces the ink consumption because it has a specific gravity which is about four times less heavier than the vitrifiable ceramic paints which have commonly been used for the decoration of glass bottles, providing a greater yield per weight unit and saves energy and space because it does not need big furnaces for heating the paint;
It is still a main object of the present invention, to provide an ultraviolet radiation curable organic ink composition, of the above disclosed nature, which provides more intense and bright colors and a more wide range of colors than the ceramic paints.
It is additionally a main objective of the present invention, to provide a process for the preparation and application of an ultraviolet radiation curable organic ink composition specially suitable for glass substrates, by which all of the above desired disclosed properties are imparted to the glass substrates, products or bottles.
These and other additional objects and advantages of the present invention will be evident to those persons having ordinary skill in the art, from the following detailed description of the invention with reference to specific embodiments thereof.